You cannot deny that you know that in the city of Rome upon Peter first the chair of the bishop was conferred, in which sat the head of all the Apostles, Peter, whence also he was called Cephas, in which one chair unity should be preserved by all, lest the other Apostles should each stand up for his own chair, so that now he should be a schismatic and a sinner who should against this one chair set up another. – Saint Optatus